OP25 tuning question

[DRL-XM43]

One of my P25 PII trunk systems suddenly would not light up.

Eventually I found that by using the "." tuning feature to a value of (500) did the trick.

So I tried applying a ppm correction value to the command line using -q, however I can not seem to come up with an equivalent value that works.

Can anyone suggest what the -q value should be? Or another way to achieve the effect automatically.

 

[boatbod]

One of my P25 PII trunk systems suddenly would not light up.

Eventually I found that by using the "." tuning feature to a value of (500) did the trick.

So I tried applying a ppm correction value to the command line using -q, however I can not seem to come up with an equivalent value that works.

Can anyone suggest what the -q value should be? Or another way to achieve the effect automatically.

PPM tuning correction is preferred for large offsets (>350). 1 ppm is equivalent to your tuned frequency in Mhz as the same number of Hz offset.
e.g. 1ppm at 773.000Mhz = 773 Hz tuning correction. In all probability you only need a +/- 1ppm correction for a 500hz correction.

Best way to see it in action is to watch what happens to the mixer plot (#5) when you make small changes to the -q ppm value. Try to make the signal peak symmetrical about the central tuning line.

 

[DRL-XM43]

PPM tuning correction is preferred for large offsets (>350). 1 ppm is equivalent to your tuned frequency in Mhz as the same number of Hz offset.
e.g. 1ppm at 773.000Mhz = 773 Hz tuning correction. In all probability you only need a +/- 1ppm correction for a 500hz correction.

Best way to see it in action is to watch what happens to the mixer plot (#5) when you make small changes to the -q ppm value. Try to make the signal peak symmetrical about the central tuning line.

Consider me solved LOL Thanks as usual boatbod.

So, it turns out I had set -q 1 although it does not sound like much it should have been zero! (much to my surprise)

Zero ppm adjustment is a testament to my NooElectric smart dongles which certainly appear to be dialed right in.

Anyway thanks again for the ppm insights - much appreciated.